STMicroelectronics LD1117D18

Overview

LD1117D18 from STMicroelectronics is a fixed-output 1.8 V low-dropout linear voltage regulator delivering up to 800 mA, featuring 1.0 V typical dropout at 100 mA, ±1 % output voltage tolerance at 25 °C, and 75 dB supply voltage rejection at 120 Hz-used in embedded power rails for microcontrollers and sensors requiring stable low-voltage bias.

For engineers reviewing the LD1117D18 datasheet, LD1117D18 pinout, LD1117D18 application, or LD1117D18 equivalent, key selection criteria include dropout performance under load, thermal resistance in SOT-223/DPAK packages, output voltage stability across temperature, and minimum 10 µF output capacitor requirement for stability.

Technical Context

The LD1117D18 employs an NPN pass transistor architecture, enabling high efficiency by routing quiescent current primarily into the load rather than ground-unlike PNP-based regulators. Its internal bandgap reference and trimming circuitry achieve tight ±1 % output accuracy at 25 °C and maintain ≤0.5 % temperature stability over –40 to +125 °C.

It integrates thermal shutdown and current limiting, with dropout voltage rising only marginally from 1.0 V (100 mA) to 1.2 V (800 mA) across full operating temperature range. The device requires no external compensation beyond a single 10 µF ceramic or tantalum output capacitor for stability.

Key Specifications

Pinout & Package

LD1117D18 is available in SOT-223, DPAK (TO-252), SO-8, and TO-220 packages. The SOT-223 and DPAK variants are most common for surface-mount applications, offering optimized thermal performance and board space savings. The exposed tab is electrically connected to V_OUT.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output LDO regulator applications.

Compared with TLV1117-18CDCYR, LD1117D18 offers lower dropout and tighter tolerance but higher quiescent current; versus MCP1700-1802E/MB, it delivers 3.2× more current with integrated protection-making it suitable for primary MCU supply where robustness and headroom are critical.

Availability

LD1117D18 is available at Aetrix Electronics and suitable for industrial automation controllers, automotive body electronics, medical wearable sensor hubs, and IoT edge nodes requiring stable component supply with long lifecycle visibility.

Supply support for LD1117D18 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The LD1117 series belongs to ST's general-purpose linear regulator product line, designed specifically for cost-sensitive, space-constrained applications needing reliable fixed- or adjustable-voltage regulation with minimal external components.

FAQ

What is the minimum input voltage required for LD1117D18 to regulate at full 800 mA load?

The minimum input voltage is determined by dropout: at 800 mA and 125 °C, V_DROP reaches 1.2 V. Therefore, V_IN(MIN) = 1.8 V + 1.2 V = 3.0 V. For reliable operation with margin, ST recommends ≥3.3 V input under worst-case thermal conditions.

Can LD1117D18 be used with ceramic output capacitors?

Yes-ST specifies stability with ≥10 µF ceramic, tantalum, or aluminum electrolytic capacitors. Ceramic types are preferred for low ESR and compact size; ensure capacitance remains ≥10 µF after DC bias derating, especially with X5R/X7R dielectrics.

Does LD1117D18 require an input capacitor?

An input capacitor is not mandatory per datasheet, but ST recommends a 1 µF ceramic capacitor placed close to the IN pin to suppress high-frequency noise and improve transient response-particularly when input source impedance is high or trace inductance is significant.

How does thermal performance differ between SOT-223 and DPAK packages?

DPAK offers superior thermal performance: R_thJA = 100 °C/W vs. 110 °C/W for SOT-223, and R_thJC = 8 °C/W vs. 15 °C/W. This allows ~15 % higher continuous power dissipation in DPAK before reaching 125 °C junction limit-critical for 800 mA loads at elevated ambient temperatures.